1. Field of the Invention
The present invention relates to printing apparatuses with cutter mechanisms. More particularly, the present invention is suitable for a printing apparatus having a partial cutting function for partially cutting roll-type recording paper while leaving an uncut portion.
2. Description of the Related Art
FIG. 10 illustrates an example of the structure of a printing apparatus with a cutting mechanism according to the related art. As illustrated in FIG. 10, roll-type recording paper 100 is arranged such that the recording paper 100 extends through an area between a thermal head 10 of a printing mechanism and a platen roller 11 of a paper-feeding mechanism. The recording paper 100 is subjected to printing by the thermal head 10, and is conveyed by the platen roller 11 such that the recording paper 100 passes through an area between a fixed blade 12 and a movable blade 13 included in the cutter mechanism and is discharged to the outside through a discharge port 16 between a front cover 14 and a rear cover 15. When the distance of conveyance of the recording paper 100 reaches a predetermined distance, the platen roller 11 stops conveying the recording paper 100. In addition, the thermal head 10 stops printing and the recording paper 100 is cut by the cutter mechanism. More specifically, a cutter driving device 17 causes the movable blade 13 to slide toward the fixed blade 12 while the recording paper 100 is placed between the movable blade 13 and the fixed blade 12, thereby cutting the recording paper 100.
A printing apparatus is known which has a partial cutting function for leaving an uncut portion in the process of cutting the recording paper 100 in addition to a full cutting function for completely cutting the recording paper 100. In this type of printing apparatus, the movable blade 13 has a V-shaped cutting edge. The movable blade 13 moves toward the fixed blade 12 that is opposed to the movable blade 13 with the recording paper 100 placed therebetween, and slides along the fixed blade 12 while being pressed against the fixed blade 12. Accordingly, the recording paper 100 is gradually cut from the ends thereof in the width direction toward the center. In a partial cutting process, the sliding of the movable blade 13 is stopped immediately before an end portion of the V-shaped cutting edge at the center of the movable blade 13 reaches the fixed blade 12. In this case, a central portion of the recording paper 100 in the width direction is left uncut. In the cutter mechanism having the above-described structure, a movable-blade receiving area 18 having a width that is larger than or equal to the width of the movable blade 13 (larger than or equal to the width of the recording paper 100) is provided to receive the movable blade 13 that slides into along the fixed blade 12.
In the case where the recording paper 100 is partially cut, a portion of the recording paper 100 that is placed in the printing apparatus and that is to be subjected to printing next is partially connected to a portion of the recording paper that has been discharged to the outside of the printing apparatus through the discharge port 16 (hereinafter referred to as “downstream connected recording paper 101”). Therefore, unless the downstream connected recording paper 101 is removed by an operator, the next portion of the recording paper 100 is subjected to printing while the downstream connected recording paper 101 is partially connected thereto. In the following descriptions, the recording paper 100 and the downstream connected recording paper 101 that are partially connected to each other are called “continuous paper”.
A leading end of the recording paper 100 that is to be subjected to printing next is at the position of the cutter mechanism (at the position of the fixed blade 12). Therefore, if the next printing operation is continuously performed from this state, a blank area having a dimension corresponding to the distance between the thermal head 10 and the fixed blade 12 is formed at the leading end of the recording paper 100. To reduce the wasted blank area in the recording paper 100, it is necessary to rotate the platen roller 11 in a reverse direction and convey the recording paper 100 backward (toward the upstream side in the conveying direction) before starting the next printing operation. The conveyance in this direction is hereinafter referred to as “backward feeding”. FIG. 10 illustrates the state in which the recording paper 100 has been fed backward by a predetermined distance.
However, when the recording paper 100 is fed backward, the downstream connected recording paper 101, which has been subjected to the previous printing operation and is partially connected to the recording paper 100, is also fed backward together with the recording paper 100. At this time, a cut portion of the downstream connected recording paper 101 will possibly enter the movable-blade receiving area 18, undesirably causing a break of an end thereof. In addition, the downstream connected recording paper 101 will be possibly stuck in the movable-blade receiving area 18, undesirably causing a break of the uncut portion at which the downstream connected recording paper 101 is connected to the recording paper 100. Further, the downstream connected recording paper 101 will be possibly folded in an accordion style, undesirably causing a paper jam.
Accordingly, Japanese Unexamined Patent Application Publication No. 2005-335315 (hereinafter referred to as Patent Document 1), for example, proposes a printer in which spherical members for suppressing partially cut continuous paper from being raised are disposed downstream of the fixed blade in the conveying direction so that the continuous paper can be prevented from being damaged. According to the printer described in Patent Document 1, the continuous paper can be fed backward without causing a cut portion of base paper to curl and be caught by the fixed blade, and therefore the continuous paper can be prevented from being damaged.
However, the related art described in Patent Document 1 cannot completely eliminate the risk that the downstream connected recording paper 101 that is partially cut will enter the movable-blade receiving area 18 and be bent, the risk that the uncut portion at which the recording paper 100 is connected to the downstream connected recording paper 101 will break, and the risk that the downstream connected recording paper 101 will be folded in an accordion style and cause a paper. More specifically, there are large gaps and steps between the fixed blade and the spherical members. Therefore, in the case where, for example, a small-diameter paper roll in which paper is highly curved is used as the recording paper 100 or the recording paper 100 is deformed by being left in a low-temperature environment or a high-temperature, high-humidity environment, there is a high possibility that an end portion of the downstream connected recording paper 101 will enter the movable-blade receiving area 18 or be stuck in the movable-blade receiving area 18 during backward feeding.
Even if the backward feeding can fortunately be performed without causing an end portion of the downstream connected recording paper 101 to be stuck in the movable-blade receiving area 18, there is a risk that an end portion of the recording paper 100 will enter the movable-blade receiving area 18 and cause a paper jam when the recording paper 100 is conveyed forward (toward the downstream side in the conveying direction) by the platen roller 11 in the next printing operation. The conveyance in this direction is hereinafter referred to as “forward feeding”.